How Obama is profiting from a Romney adviser's theory about American power

Mitt Romney likes to say Barack Obama has resigned himself to a world in which the U.S. is no longer a mighty power. "Our President thinks America is in decline," Romney said in December. A Romney-campaign policy paper elaborates, saying Obama's team is not only reconciled to a weakened America but sees that decline "as both inexorable and a condition that can and should be managed for the global good rather than reversed."

As Romney runs against a President who has killed Osama bin Laden, neutralized al-Qaeda and toppled Muammar Gaddafi, this larger critique of Obama's vision might be Romney's best--and...